The invention relates generally to Global Navigation Satellite System (GNSS) receivers and more particularly to a method and an apparatus for computing multiple precise locations using differential carrier phases of a GNSS satellite signal by synchronizing the clocks between the master receiver and the slave receiver. It further relates to a technique of connecting a plurality of antennas to the slave receiver, which can be switched on to measure each antenna's relative location to the master antenna for monitoring long-term deformation. Still further, the invention relates to surveying and measuring applications of a multi-antenna, single-receiver vector GNSS system using RTK techniques.